Complicanze infettive locali precoci e tardive nella chirurgia otologica

La via retroauricolare rappresenta l’approccio di scelta nel trattamento dell’otite media cronica. Nelle procedure “sporche” l’incidenza della complicanza infettiva locale è del 10%. Il presente studio analizza le infezioni del sito chirurgico dopo la chirurgia dell’otite media cronica e ne investiga i potenziali fattori predittivi. Il presente studio, dal design osservazionale prospettico, ha incluso pazienti affetti da otite media cronica e candidati alla chirurgia mediante approccio retroauricolare. Sono state definite precoci le complicanze postoperatorie insorte entro i 30 giorni e tardive quelle insorte oltre i 30 giorni. Sono stati analizzati i dati di 102 pazienti. Sono stati registrati 4 casi (3,9%) di infezione precoce, per la quale è stata evidenziata un’associazione significativa con l’antibioticoterapia preoperatoria, l’orecchio in fase secernente all’esame otoscopico preoperatorio, una classe III (contaminato) nella classificazione delle ferite chirurgiche, indice NNIS (National Nosocomial Infection Surveillance) >1 e assunzione di antibiotici per OS nel postoperatorio. Sono state inoltre registrate 7 complicanze tardive (7,1%), occorse fra i 90 e i 160 giorni dall’intervento, significativamente correlate alla presenza di otorrea nei sei mesi precedenti la chirurgia, una durata del tempo chirurgico inferiore o uguale a 60 minuti, una tecnica aperta e all’uso della colla di fibrina. L’infezione del sito chirurgico sembra essere associata ai fattori correlati allo stato infiammatorio dell’orecchio medio al momento della chirurgia nelle infezioni precoci e all’infiammazione cronica nelle infezioni tardive

Efecto del antígeno excretor-secretor de leishmania braziliensis sobre la fagocitosis en macrófagos.

Leishmania braziliensis es un flagelado digénico que causa patología en mamíferos.El insecto vector inocula formas promastigotes del parásito en el torrente circulatorio delhospedador. Los parásitos deben ser endocitados rápidamente por los macrófagos u otrosfagocitos, en los que se reproduce como amastigote dentro de una vacuola parasitófora; lospromastigotes que no son internalizados mueren. Se sabe que la activación de los macrófagos, pormoléculas como los lipopolisacáridos (LPS) por ejemplo, producen mediadores químicos queregulan la respuesta inmune humoral y determinan la producción de interleuquinas Th1 o Th2, perose desconoce el efecto de la activación de los macrófagos sobre el proceso de fagocitosis. Por otraparte, se ha visto que el antígeno excretor-secretor producido por promastigotes (AESPL) de L.donovani activa a macrófagos murinos para la producción de interleuquinas pero no se conoce suefecto sobre el proceso de fagocitosis

Current Treatment of Endolymphatic Sac Tumor of the Temporal Bone

An endolymphatic sac tumor (ELST) is a rare, indolent but locally aggressive tumor arising in the posterior petrous ridge. Patients present with sensorineural hearing loss and tinnitus. As the tumor progresses, patients may experience vertigo, ataxia, facial nerve paresis, pain and otorrhea. Most patients present in their 4th or 5th decade with a wide age range. Patients with von Hippel–Lindau disease have an increased likelihood of developing ELST. Histologically, ELST is a low-grade adenocarcinoma. As it progresses, it destroys bone and extends into adjacent tissues. The likelihood of regional or distant metastases is remote. The optimal treatment is resection with negative margins. Patients with positive margins, gross residual disease, or unresectable tumor are treated with radiotherapy or radiosurgery. Late recurrences are common, so long follow-up is necessary to assess efficacy. The likelihood of cure depends on tumor extent and is probably in the range of 50–75%

Steady state thermomechanical modelling of friction stir welding

International audienceThis paper presents a computational method for the simulation of a welding process called friction stir welding. This simulation is divided into two main steps. The first one uses an Eulerian description of the thermomechanical problem; a 3D mixed finite element model based on a computational fluid dynamics package is used to establish the material flow, the temperature and the pressure fields during the process. These results are compared with experimental data. The second step of the simulation is more original. A part of the initial geometry is extracted in order to evaluate the material flow in a local domain around the tool. A steady state algorithm is then used to calculate the residual state induced by the process. This calculation takes into account the whole mechanical history of the material because the algorithm is based on an integration along the trajectories of the particles. Finally, the residual stresses of a friction stir welded assembling are evaluated. It should be noted that only the steady state phase of the process is simulated, which leads to a substantial reduction of computational time

Modelling of the residual state of friction stir welded plates

International audienceThis paper presents a steady-state simulation of friction stir welding based on a prior computational method developed in [Bastier, A., Maitournam, M.H., Dang Van, K., Roger, F., 2006. Steady state thermomechanical modelling of friction stir welding. Sci. Technol. Weld. Joining 11 (3), 278–288]. This simulation includes two main steps. The first one uses an Eulerian description of the thermomechanical problem: a 3D-mixed Finite Element Model based on a Computational Fluid Dynamics package is used to establish the material flow and the temperature field during the process. In the second step, a steady-state algorithm based on an elastoviscoplastic constitutive law is used to estimate the residual state induced by the process. The steady-state assumption and the original elastoviscoplastic constitutive law are two key features of the present model. This calculation takes into account the whole thermal, metallurgical and mechanical history of the material since the algorithm is based on an integration along the path lines of the particles. The material considered is a 7050 aluminium alloy. It is observed that the longitudinal residual stress field has a two peaks profile: these two peaks are situated in the zone of high gradient of dissolved precipitates fraction. Finally, a parametric study about the influence of welding and rotational speeds is carried out. This parametric study shows that the higher the welding speed and the lower the rotational speed, the lower the temperatures and the lower residual distortions